Hey, we are moving out of an old email marketing platform into Marketo. Our contacts database has over 1 million contacts in it, but we will only have space for half of that in Marketo. Before syncing CRM to Marketo, I believe I need to mark some of our contacts as "do not sync to marketo". I am attempting to use data from our old marketing platform to identify those for "do not sync..."

We are a non-profit association, and I am initially considering saying "if you have not opened an email from us in 1 year then i will not sync you". That seems like a long time period, but no previous contact cleaning has been done.

Is there a best practice/standard for how long someone can be disengaged before removing from your list?

In my eyes this is a really business specific question, what are you trying to accomplish and is there a possibility to re-engage these leads is what I would start asking yourself? Depending on the engagement level we have multiple tiers for programs we shuffle people through Engaged=emailed most frequently, not engaged=slow email drip of less frequent emails that are more pertinent to the lead, and then finally greater than 6 months we run through a re-engagement program and if no engagement we retire them.

I would take a hard look at your analytics and base decisions off of these rather than gun intuition. Leads/Contacts are valuable!

I don't think there is a real best practice, it would all depend upon your industry, product, customer etc... I would say its more about what you say fits best for you. Do you expect your customers to engage with you often? What is a typical customer like?

You could also try using a service like Neverbounce to run your list through first. They will identify old and useless emails address which could help to significantly reduce your list before you begin to remove anyone else.

It is a pretty big mix, a lot of our primary audience is the staff or members of our member organizations. However, the largest (by number) of contacts we have are most likely individual addresses though.